Frog Diversity and Population Trends in Andasibe, Madagascar

Facing immediate threats such as habitat loss, emerging infectious diseases, and climate change, the frog populations of the Madagascar rainforest, one of the richest amphibian diversity hotspots in the world, are an important focus for monitoring programs. This study focused on assessing the general diversity, key species population trends, and monitoring effectiveness of the Analamazaotra Forest Station’s amphibian community, a population of over forty species within Andasibe, Madagascar. Building on a long-term monitoring program that began in 2012, visual encounter surveys were conducted over a two-week period in November 2015 along the edge and within the interior of the forest area managed by Association Mitsinjo. The current twenty-four transects were found to be an effective means of monitoring amphibian populations given species abundance curves and an individual assessment of each transect. Rank abundance curves, Simpson’s Diversity Indexes, and a Jaccard’s Index were calculated as diversity assessment values using three years of data collection. From species evenness and richness assessments, the interior of the forest appeared to be unchanging in terms of diversity (stabilizing around a SDI of 0.91) while the forest edge had a decrease in diversity since 2013 (2013 SDI, 0.98; 2015 SDI, 0.82). These trends did not support expected diversity increases given the recovering status of the Analamazaotra Forest Station, since its protection in 2003, suggesting that these results may have been influenced by the seasonality effect of edge preference, the forest’s carrying capacity, and inconsistent surveys. For monitoring purposes, seasonality abundance baselines were calculated for the past four years of eleven key species. These eleven baseline species can be tracked in future years to assess population declines and judge habitat quality and forest health